Bridging network devices in a hybrid communication network

ABSTRACT

A hybrid bridge can implement functionality for selectively populating its bridge tables based on preferred transmission routes to influence other network devices to transmit frames based on the preferred transmission routes. The hybrid bridge determines a preferred transmission route for communicating with each network device in the hybrid communication network. For each of the network devices, it is determined whether the hybrid bridge is part of the preferred transmission route associated with the network device. Depending on whether the hybrid bridge is part of the preferred transmission route to the network device and/or whether a network interface of the hybrid bridge is a transmit or a receive interface on the preferred transmission route, a local bridge table or a remote bridge table of the network interface can be populated with at least the address of a destination network device.

BACKGROUND

Embodiments of the inventive subject matter generally relate to thefield of communication networks and, more particularly, to bridgingnetwork devices in a hybrid communication network.

Hybrid communication networks typically comprise multiple networkdevices that implement multiple networking technologies (e.g., wirelesslocal area network (WLAN) technologies, powerline communicationtechnologies, Ethernet, etc.). Typically, the communication mechanismsand protocol specifics (e.g., device and topology discovery, bridging toother networks, etc.) are unique to each networking technology. Themultiple networking technologies are typically interconnected usingbridging-capable network devices that forward frames between thedifferent network technologies and media to form a single, extendedcommunication network. Hybrid communication networks typically presentmultiple frame delivery routes between any two network devices in thehybrid communication network.

SUMMARY

Various embodiments for bridging network devices in a hybridcommunication network are disclosed. In one embodiment, a hybrid networklayer of a hybrid bridge device of a hybrid communication networkdetermines a preferred transmission route for communicating with a firstof a plurality of network devices of the hybrid communication networkbased, at least in part, on one or more topology discovery messagesreceived from one or more of the plurality of network devices of thehybrid communication network. The hybrid network layer then determineswhether the hybrid bridge device is part of the preferred transmissionroute associated with the first of the plurality of network devices. Abridge table associated with the hybrid bridge device is populated withan identifier associated with the first of the plurality of networkdevices based on whether the hybrid bridge device is part of thepreferred transmission route associated with the first of the pluralityof network devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The present embodiments may be better understood, and numerous objects,features, and advantages made apparent to those skilled in the art byreferencing the accompanying drawings.

FIG. 1 is a conceptual diagram illustrating an example mechanism forbridging network devices in a hybrid communication network;

FIGS. 2A and 2B depict a flow diagram illustrating example operations ofa hybrid bridge for populating a local bridge table and a remote bridgetable;

FIG. 3 is a flow diagram illustrating example operations for using thebridge tables to route a frame to a destination network device; and

FIG. 4 is a block diagram of one embodiment of an electronic deviceincluding a mechanism for bridging network devices in a hybridcommunication network.

DESCRIPTION OF EMBODIMENT(S)

The description that follows includes exemplary systems, methods,techniques, instruction sequences, and computer program products thatembody techniques of the present inventive subject matter. However, itis understood that the described embodiments may be practiced withoutthese specific details. For instance, although examples refer tooperations for bridging Ethernet devices and powerline communication(PLC) devices (e.g., HomePlug® AV devices), embodiments are not solimited. In other embodiments, the bridging operations described hereincan be employed to bridge network devices that implement other suitablecommunication protocols (e.g., for bridging Ethernet devices withMultimedia over Coax Alliance (MoCA®) devices, etc.). In otherinstances, well-known instruction instances, protocols, structures, andtechniques have not been shown in detail in order not to obfuscate thedescription.

A network interface (e.g., a PLC interface and/or MoCA interface)associated with a network bridge can maintain two types of bridgetables—a local bridge destination address table (LBDAT) and a remotebridged address table (RBAT). The network interface of the networkbridge (“network bridge interface”) maintains the LBDAT to identifywhich destination devices are directly reachable via thebridging-capable network bridge interface. Each network interface (e.g.whether or not a bridging-capable network interface) can maintain theRBAT that indicates to which network bridge a frame should be forwardedso that the frame reaches an intended destination device. In accordancewith conventional bridging functionality, the network bridge interfacecan use source address learning to populate its local bridge table(e.g., the LBDAT) and to determine which network devices are reachablevia the network bridge interface. In accordance with the conventionalbridging functionality, network interfaces associated with other networkdevices in the communication network can use the local bridge tables(received from the network bridge interface) to populate theirrespective remote bridge table (e.g., an RBAT). The RBAT can enable theother network interfaces to identify the network bridge interface viawhich a destination network device is accessible. For example, when aconventional PLC-to-Ethernet bridge receives a frame at its Ethernetinterface, it can record the source address of the received frame in itslocal bridge table (e.g., associated with the PLC interface). If theconventional PLC-to-Ethernet bridge receives (at its PLC interface) aframe intended for an Ethernet device listed in its local bridge table,the conventional PLC-to-Ethernet bridge can forward the received frameto the Ethernet device. However, the hybrid communication network canoffer multiple transmission routes between any two network devices.Therefore, conventional bridging functionality is typically notsufficient to properly support bridging in the hybrid communicationnetwork. Multiple transmission routes between two network devices canresult in communication loops and frame replication. Also, because theconventional bridging functionality uses source address learning topopulate the local and remote bridge tables, this can result inunintended discarding of frames, changes in frame transmission routes,use of non-optimal frame transmission routes, and unnecessary floodingof frames in the hybrid communication network.

A hybrid networking sub-layer of a hybrid device configured as a networkbridge (“hybrid bridge”) can be configured to execute functionality toselectively populate its local bridge table and remote bridge tablebased on the hybrid networking sub-layer's knowledge of the topology ofthe hybrid communication network and the preferred transmission routes.A hybrid bridge can determine, based on received topology discoverymessages, a preferred transmission route for communicating with eachnetwork device of the hybrid communication network via its networkinterfaces (“hybrid bridge interfaces”) that support bridging (or frameforwarding). For each of the network devices, if the hybrid bridgeinterface (e.g., a HomePlug AV interface) is a receive interface on thepreferred transmission route to the network device, the hybrid bridgeinterface can populate its local bridge table with the address of thenetwork device to indicate that the network device is reachable via thehybrid bridge interface. If the hybrid bridge interface is not part ofthe preferred transmission route to the network device or if the hybridbridge interface is a transmit interface on the preferred transmissionroute to the network device, the hybrid bridge interface can identifyanother hybrid bridge interface (e.g., of another hybrid bridge) that isa receive interface on the preferred transmission route. The hybridbridge interface can populate its remote bridge table to indicate thatany frame destined for the network device should be forwarded via theother hybrid bridge. Such a hybrid bridging mechanism for bridgingdevices in a hybrid communication network can help prevent unintendeddiscarding of frames, unintended route changes, communication loops, andframe replication. By configuring the hybrid bridges to selectivelypopulate their local bridge tables and remote bridge tables inaccordance with the preferred transmission routes, the hybrid bridgingmechanism can influence the content of the remote bridge tables of thelegacy devices in the hybrid communication network and can influence thelegacy devices to use the preferred transmission routes. Thus, thehybrid bridging mechanism can enable not only the hybrid devices butalso the legacy devices to efficiently route frames in the hybridcommunication network.

FIG. 1 is a conceptual diagram illustrating an example mechanism forbridging network devices in a hybrid communication network 100. Thehybrid communication network 100 comprises hybrid devices 102 and 122,legacy Ethernet devices 114, 116, and 128, and a legacy PLC device 118.In some embodiments, the hybrid devices 102 and 122 can be networkdevices that comprise multiple network interfaces and that implement aplurality of communication protocols (which may also be referred to asaccess technologies) to couple the hybrid device to a plurality ofheterogeneous communication networks. In another embodiment, the hybriddevices 102 and 122 can be network devices that support hybridnetworking topology messages and related functionality (e.g., networkdevices that comprise a hybrid networking layer). The hybrid device 102comprises two network interfaces—an Ethernet interface 108 and a PLCinterface 110 that couple the hybrid device 102 to an Ethernet and apowerline network 140 respectively. Likewise, the hybrid device 122comprises at least an Ethernet interface (not shown) and a PLC interface(not shown) that couple the hybrid device 122 to the Ethernet and thepowerline network 140 respectively. It is noted that in otherembodiments, the hybrid devices 102 and 122 can comprise the same numberof network interfaces, different number of network interfaces, same typeof network interfaces, or different type of network interfaces. Thelegacy devices comprise a single interface that couples the legacydevice to a corresponding single communication network. In FIG. 1, thelegacy Ethernet devices 114, 116, and 128 each comprises a singleEthernet interface that couple the Ethernet devices 114, 116, and 128 tothe Ethernet. Likewise, the legacy PLC device 118 comprises a single PLCinterface that couples the PLC device 118 to the powerline network 140.In the hybrid communication network 100 of FIG. 1, the Ethernetinterface 108 of the hybrid device 102 is coupled to the legacy Ethernetdevices 114 and 116. The PLC interface 110 of the hybrid device 102 iscoupled to the legacy PLC device 118. The hybrid device 122 is coupledto the legacy Ethernet device 128 (via its Ethernet interface) and tothe legacy PLC device 118 (via its PLC interface).

In FIG. 1, the hybrid devices 102 and 122 are each configured asbridging-capable network devices and are herein referred to as “hybridbridge devices” or “hybrid bridges.” In the example of FIG. 1, thehybrid bridges 102 and 122 are PLC-to-Ethernet bridges that forwardframes received from PLC devices (via the PLC interface) to Ethernetdevices (via the Ethernet interface). If the powerline technologyemployed in the hybrid communication network 100 is HomePlug® AV, thehybrid devices 102 and 122 can each be HomePlug AV-to-Ethernet bridges.As discussed above, each hybrid bridge 102 and 122 can comprise at leasttwo bridge tables—a local bridge table and a remote bridge table. Forexample, the local bridge table indicates which Ethernet devices can beaccessed from the hybrid bridge via the preferred transmission route,and the remote bridge table indicates how to access those Ethernetdevices that cannot be accessed from the hybrid bridge via the preferredtransmission route. In FIG. 1, the hybrid bridge 102 comprises a localbridge table 104 and a remote bridge table 106; while the hybrid bridge122 comprises a local bridge table 124 and a remote bridge table 126.The legacy PLC device (and other legacy devices and hybrid devices thatare not configured as bridging-capable devices) typically do notcomprise a local bridge table and only comprise a remote bridge table.In FIG. 1, the legacy PLC device 118 comprises a remote bridge table130. Operations for populating the local bridge tables and the remotebridge tables will further be described below in FIGS. 1-2.

The hybrid bridges 102 and 122 can each be electronic devices configuredto implement a plurality of communication protocols or accesstechnologies, such as a laptop computer, a tablet computer, a mobilephone, a smart appliance, a gaming console, an access point, a desktopcomputer, or other suitable electronic devices. In some implementations,the hybrid bridge 102 also comprises a communication unit 112 configuredto implement at least a subset of communication protocols or accesstechnologies in a hybrid communication network. The communication unit112 can implement functionality described below in FIGS. 1-3 toselectively populate the local bridge table 104 and the remote bridgetable 106 according to the preferred transmission route forcommunicating with the other network devices of the hybrid communicationnetwork 100. Although not depicted in FIG. 1, the hybrid bridge 122 mayalso comprise a communication unit that implements the functionalitydescribed below in FIGS. 1-3. In FIG. 1, the legacy PLC device 118comprises a communication unit 120. The communication unit 120 canexecute operations described below in FIGS. 1-3 to populate the remotebridge table 130 and to determine how to route a frame to an Ethernetdevice. In some embodiments, the communication units of the hybridbridges 102 and 122 can be implemented as part of the hybrid networkingsub-layer of the respective hybrid bridges 102 and 122. In someembodiments, the communication unit of the hybrid bridges 102 and 122and the legacy PLC device 118 can each be implemented on asystem-on-a-chip (SoC), an application specific integrated circuit(ASIC), or another suitable integrated circuit to enable networkcommunications on their respective network device. In some embodiments,the communication units may each comprise one or more processors andmemory, and may each be implemented in one or more integrated circuitson one or more circuit boards of their respective network device.

At stage A, the communication unit 112 populates bridge tablesassociated with the hybrid bridge 102 based, at least in part, onnetwork topology messages exchanged between the hybrid devices 102 and122 in the hybrid communication network 100. Each of the hybrid devices102 and 122 in the hybrid communication network 100 typically transmittopology discovery messages that include information about the hybriddevice that transmitted the topology discovery message and informationabout its neighbor (hybrid and legacy) devices. For example, the hybridbridge 102 may transmit topology discovery messages indicating that ithas two network interfaces—the Ethernet interface 108 and the PLCinterface 110, that the Ethernet devices 114 and 116 are connected toits Ethernet interface 108, and that the PLC device 118 is connected toits PLC interface 110. The topology discovery message can also comprisea list of the network interfaces through which the hybrid bridge 102supports frame forwarding. In FIG. 1, the communication unit 112 mayindicate that the hybrid bridge 102 supports PLC-to-Ethernet bridgingvia the PLC (e.g., HomePlug AV) interface 110. In one embodiment, thehybrid bridge 102 can indicate it supports the hybrid bridgingfunctionality through the PLC interface 110 by setting one or morepredetermined bits in a management message transmitted from the PLCinterface 110 (e.g., by setting a bridging station flag (BSF) in aCM_BRG_INFO.CNF management message for a HomePlug AV interface).However, if the PLC interface 110 of the hybrid device 102 does notsupport the hybrid bridging functionality, the topology discoverymessage broadcast by the hybrid device 102 may not include the PLCinterface 110 in the list of network interfaces of the hybrid device 102through which frames can be forwarded. Likewise, the hybrid bridge 122may transmit topology discovery messages identifying its networkinterfaces (not shown in FIG. 1), indicating that the Ethernet device128 is connected to its Ethernet interface, and that the PLC device 118is connected to its PLC interface. In response to receiving topologydiscovery messages from other hybrid devices in the hybrid communicationnetwork 100, the hybrid bridge 102 (e.g., the hybrid networkingsub-layer) can use any suitable techniques to determine the topology ofthe hybrid communication network 100. The hybrid bridge 102 (e.g., thehybrid networking sub-layer) can also determine, based on the receivedtopology discovery messages, the preferred transmission route betweenitself and any other network device (whether legacy device or hybriddevice) in the hybrid communication network 100. Likewise, the hybridbridge 122 (e.g., the hybrid networking sub-layer) can also determinethe topology of the hybrid communication network 100 and the preferredtransmission route between itself and any other network device. In someembodiments, after the hybrid bridge 102 determines the preferredtransmission route between itself and the other network devices, thehybrid bridge 102 can transmit a preferred route message to notify theother hybrid devices 122 of the preferred transmission routes associatedwith the hybrid bridge 102.

Each hybrid bridge (e.g., the hybrid bridge 102) can selectivelypopulate its local bridge table (e.g., the local bridge table 104) toadvertise the addresses of only those network devices for which thehybrid bridge 102 is part of the preferred transmission route. Withreference to the example of FIG. 1, the Ethernet devices 114, 116, and128 may be accessible via both the hybrid bridges 102 and 122. However,based on exchanging the topology discovery messages (and the preferredroute messages), the communication unit 112 may determine that thehybrid bridge 102 is part of the preferred transmission route to theEthernet devices 114 and 116 and that the hybrid bridge 122 is part ofthe preferred transmission route to the Ethernet device 128.Specifically, the communication unit 112 may determine that the PLCinterface 110 is a receive interface on the preferred transmission routeto the Ethernet devices 114 and 116. Accordingly, in this specificexample shown in FIG. 1, the communication unit 112 can selectivelypopulate the local bridge table 104 to include only the addresses of theEthernet devices 114 and 116 and to indicate that only the Ethernetdevices 114 and 116 are accessible via the PLC interface 110 of thehybrid bridge 102 (e.g., that the Ethernet devices 114 and 116 aredirectly connected to the hybrid bridge 102). Likewise, the hybridbridge 122 may determine that its PLC interface is a receive interfaceon the preferred transmission route to the Ethernet device 128. Thecommunication unit of the hybrid bridge 122 can selectively populate thelocal bridge table 124 to advertise that only the Ethernet device 128 isaccessible via the PLC interface of the hybrid bridge 122. Each hybridbridge 102 and 122 can then transmit its local bridge table 104 and 124respectively to other network devices in the hybrid communicationnetwork 100. For example, if the hybrid bridge 102 is configured as aPLC-to-Ethernet bridge, the hybrid bridge 102 can transmit the localbridge table 104 (including the list of accessible Ethernet devices) viathe PLC interface 110 on the powerline segment 140 of the hybridcommunication network 100. Likewise, the hybrid bridge 122 can transmitthe local bridge table 124 via its PLC interface on the powerlinesegment 140 of the hybrid communication network 100.

In addition to the local bridge table, each hybrid bridge (e.g., thehybrid bridge 102) can populate (e.g., based on the received topologydiscovery messages) a remote bridge table (e.g., the remote bridge table106) for each PLC interface 110 (e.g., HomePlug AV interface). Theremote bridge table 106 can be populated according to the “next hop” PLCinterface associated with the preferred transmission route to eachdestination address (e.g., a media access control (MAC) address of eachdestination Ethernet device in the hybrid communication network). Thus,with reference to the hybrid bridge 102, the communication unit 112 maydetermine that the Ethernet device 128 is not reachable through theEthernet interface 108 of the hybrid bridge 102 via the preferredtransmission route or that the PLC interface 110 is a transmit interfaceon the preferred transmission route to the Ethernet device 128. Thecommunication unit 112 may determine that the PLC interface of thehybrid bridge 122 is a receive interface on the preferred transmissionroute to the Ethernet device 128. In response, the remote bridge table106 of the hybrid bridge 102 can be populated with a device identifier(e.g., MAC address) of the Ethernet device 128 and an identifier of thehybrid bridge device 122 (e.g., a terminal equipment identifier (TEI) ofthe PLC interface of the hybrid bridge 122). Likewise, the hybrid bridge122 may determine (e.g., based on the received topology discoverymessages) that the PLC interface 110 of the hybrid bridge 102 is areceive interface on the preferred transmission route to the Ethernetdevices 114 and 116. Accordingly, the hybrid bridge 122 can create twoentries in the remote bridge table 126—a first entry that indicates theMAC address of the Ethernet device 114 and the TEI of the PLC interface110 of the hybrid bridge 102; and a second entry that indicates the MACaddress of the Ethernet device 116 and the TEI of the PLC interface 110of the hybrid bridge 102.

After the hybrid bridges 102 and 122 generate their respective bridgetables, the hybrid bridges 102 and 122 can transmit the local bridgetables 104 and 124 respectively to other network devices of the hybridcommunication network 100. Specifically, when the hybrid bridges 102 and122 are configured as PLC-to-Ethernet bridges, the hybrid bridges 102and 122 can transmit the local bridge tables 104 and 124 respectivelyvia their respective PLC interfaces onto the powerline network segment140 of the hybrid communication network 100. As will be furtherdiscussed below, the legacy PLC devices (e.g., legacy bridge devices andlegacy non-bridge devices) on the powerline network segment 140 canpopulate their respective remote bridge tables based on the content ofthe local bridge tables 104 and 124 received from the hybrid bridges 102and 122 respectively.

At stage B, the PLC device 118 (e.g., a legacy HomePlug AV device, alegacy Ethernet-to-PLC bridge, etc.) receives the local bridge tables104 and 124 from the hybrid bridges 102 and 122 respectively andpopulates the remote bridge table 130 based on the received local bridgetables 104 and 124. The PLC device 118 (e.g., the communication unit120) can identify the network devices (e.g., the MAC addresses of theEthernet devices) that are reachable/accessible through each of thehybrid devices 102 and 122 from the received local bridge tables 104 and124. For example, based on the received local bridge tables 104 and 124,the PLC device 118 may determine that the Ethernet devices 114 and 116are accessible via the PLC interface 110 of the hybrid bridge 102 andthat the Ethernet device 128 is accessible via the PLC interface of thehybrid bridge 122. As depicted in FIG. 1, the communication unit 120 ofthe PLC device 118 can populate the remote bridge table 130 so that anyframes intended for the Ethernet devices 114 and 116 are forwarded tothe PLC interface 110 of the hybrid bridge 102, and any frame intendedfor the Ethernet device 128 is forwarded to the PLC interface of thehybrid bridge 122. In some embodiments, the remote bridge table 130 cancomprise one or more entries, each of which indicate a relationshipbetween a 48-bit destination Ethernet address (e.g., an Ethernet MACaddress) and an 8-bit PLC address (e.g., a terminal equipment identifier(TEI)) of a next hop PLC device. Thus, the remote bridge table 130 ofthe PLC device 118 can comprise three entries—a first entry thatcomprises the MAC address of the Ethernet device 116 and the TEI of thePLC interface 110 of the hybrid bridge 102; a second entry thatcomprises the MAC address of the Ethernet device 116 and the TEI of thePLC interface 110 of the hybrid bridge 102; and a third entry thatcomprises the MAC address of the Ethernet device 128 and the TEI of thePLC interface of the hybrid bridge 122.

As discussed above in stage A, each of the hybrid bridges 102 and 122selectively populate their local bridge table based on the preferredtransmission routes from their respective PLC interfaces to the Ethernetdevices 114, 116, and 128. Because the legacy PLC device 118 uses thelocal bridge tables 104 and 124 to populate the remote bridge table 130,the hybrid bridges 102 and 122 can indirectly influence the transmissionroute subsequently selected by the legacy PLC device 118 and caninfluence the legacy PLC device 118 to transmit a frame via thepreferred transmission route, even though the legacy PLC device 118 maybe unaware of the existence of preferred transmission routes.

At stage C, the PLC device 118 determines to transmit a frame to thedestination Ethernet device 116 and transmits the frame to the hybridbridge 102 for forwarding to the destination Ethernet device 116 basedon the remote bridge table 130. The frame destined for the Ethernetdevice 116 can comprise an address (e.g., a 48-bit destination MACaddress) associated with the Ethernet device 116. To route the frame tothe destination Ethernet device 116, the communication unit 120 of thePLC device 118 can access the remote bridge table 130 and can determinean identifier (e.g., the TEI) of a PLC interface of a PLC-to-Ethernetbridge via which to forward the frame. In the example of FIG. 1, thelegacy PLC device 118 can determine (from the remote bridge table 130)that the frame destined for the Ethernet device 116 should betransmitted to the PLC interface 110 of the hybrid bridge 102 forforwarding to the Ethernet device 116. The legacy PLC device 118 candetermine the address (e.g., an 8-bit TEI) of the PLC interface 110 ofthe hybrid bridge 102 from the remote bridge table 130 and can transmitthe frame to the PLC interface 110 of the hybrid bridge 102.

At stage D, the hybrid bridge 102 forwards the received frame to thedestination Ethernet device 116. In some embodiments, a hybridforwarding layer of the hybrid bridge 102 can use its forwarding tablesto determine how to route the frame to the destination Ethernet device116. In other embodiments, however, the hybrid bridge 102 can use thelocal bridge table 104 and/or the remote bridge table 106 to determinehow to forward the frame to the destination Ethernet device 116. Forexample, the hybrid bridge 102 (e.g., the PLC interface 110 and/or thecommunication unit 112) can determine whether the destination Ethernetdevice 116 is reachable from the hybrid bridge 102 via the preferredtransmission route (e.g., whether the destination MAC address of theEthernet device 116 is listed in the local bridge table 104). If thedestination MAC address in the received frame is listed in the localbridge table 104, the hybrid bridge 102 can determine that thecorresponding Ethernet device (e.g., the Ethernet device 116) isreachable via the Ethernet interface 108 of the hybrid bridge 102.However, if the destination MAC address (e.g., of the Ethernet device128) in the received frame is not listed in the local bridge table 104,the hybrid bridge 102 can determine that the frame should be forwardedto the corresponding destination Ethernet device (e.g., the Ethernetdevice 128) via another hybrid bridge. The hybrid bridge 102 (e.g., thePLC interface 110 and/or the communication unit 112) can identify anentry of the remote bridge table 106 that matches the destination MACaddress in the received frame. The identified entry of the remote bridgetable 106 may also include a device identifier of another hybrid bridge122 (e.g., the TEI of the PLC interface of the hybrid bridge 122). Thehybrid bridge 102 can then forward the frame to the PLC interface of thehybrid bridge 122 for subsequent forwarding to the Ethernet device 128.

It is noted that, in various embodiments, the local bridge table 104 andthe remote bridge table 106 are distinct from the forwarding tablesassociated with the hybrid networking sub-layer of the hybrid bridge102. The local bridge table 104 and the remote bridge table 106 may beextensions to the forwarding tables associated with the hybridnetworking sub-layer. While the forwarding tables associated with thehybrid networking sub-layer control selection of an entire framedelivery route, the local and the remote bridge tables can control thePLC links (e.g., HomePlug AV links) that are a subset of the completeframe delivery route. The local and the remote bridge tables can beassociated with the PLC interfaces and can be used by the PLC interfacesto determine how to forward frames to bridge two distinct communicationtechnologies (e.g., Ethernet and HomePlug AV).

In some embodiments, the hybrid networking sub-layer of the hybridbridge 102 can populate the local bridge table 104 and the remote bridgetable 106 in addition to the forwarding tables associated with thehybrid bridge 102. The hybrid networking sub-layer can provide the localbridge table 104 and the remote bridge table 106 to the PLC interface110 of the hybrid bridge 102. In another embodiment, the PLC interface110 of the hybrid bridge 102 can indirectly derive, based on theforwarding tables and the preferred transmission routes (e.g., receivedfrom the hybrid networking sub-layer), the local bridge table 104 andthe remote bridge table 106. In another embodiment, the PLC interface110 of the hybrid bridge 102 can directly derive the local bridge table104 and the remote bridge table 106 from the forwarding tables if theMAC address of a “next hop” communication link is included in theforwarding tables received from the other hybrid devices that generatedthe forwarding tables.

Although FIG. 1 describes the operations of stages A-D with reference totwo bridging-capable hybrid devices 102 and 122, in other embodiments,the hybrid communication network 100 may also comprise nonbridging-capable hybrid devices. In other words, the hybridcommunication network may comprise at least one hybrid bridge (e.g., thehybrid bridge 102 that supports PLC-to-Ethernet bridging) and anon-bridge hybrid device. The non-bridge hybrid device may comprise, forexample, a PLC interface and an Ethernet interface but may not supportPLC-to-Ethernet bridging. In this example, the PLC interface of thenon-bridge hybrid device may not maintain a local bridge table. The PLCinterface of the non-bridge hybrid device may only maintain a remotebridge table. The PLC interface of the non-bridge hybrid device maypopulate its remote bridge table based, at least in part, on thetopology discovery messages received from the other hybrid devices ofthe hybrid communication network 100. Thus, in response to thenon-bridge hybrid device receiving a frame on its PLC interface andintended for a destination Ethernet device, the PLC interface canidentify (e.g., based on the remote bridge table) another PLC interfaceof a hybrid bridge via which to route the frame to the destinationEthernet device. Additionally, the hybrid communication network 100 maycomprise bridging-capable legacy devices (“legacy bridges”) and/ornon-bridge legacy devices. As discussed herein, the legacy bridges andthe non-bridge legacy devices can populate their remote bridge tablesbased on the local bridge tables received from the hybrid bridges of thehybrid communication network.

It is noted that although FIG. 1 is described in the context of PLC(e.g., HomePlug AV)-to-Ethernet bridging, embodiments are not solimited. In other embodiments, the bridging operations described hereincan be extended to bridging devices that implement other suitablecommunication protocols (e.g., for bridging Ethernet devices and MoCAdevices, for bridging MoCA devices and HomePlug AV devices, etc.).Although not depicted in FIG. 1, in some embodiments, the Ethernetinterfaces of the hybrid devices (and the legacy Ethernet devices) mayalso be associated with bridging tables that may be populated inaccordance with operations described above. Furthermore, it is notedthat in some embodiments, the PLC device 118 and the Ethernet devices114, 116, and 128 may not be legacy devices. For example, the PLC device118 and the Ethernet devices 114, 116, and 128 may be hybrid devicesthat do not support the bridging functionality.

FIGS. 2A and 2B depict a flow diagram (“flow”) 200 illustrating exampleoperations of a hybrid bridge for populating a local bridge table and aremote bridge table. The flow 200 begins at block 202.

At block 202, a hybrid bridge of a hybrid communication networktransmits topology messages to and receives topology messages from otherhybrid devices of the hybrid communication network. With reference tothe example of FIG. 1, the hybrid bridge 102 (e.g., the communicationunit 112) can broadcast topology messages to the other hybrid devices(e.g., the hybrid bridge 122) in the hybrid communication network 100.The topology messages can comprise information about the hybrid bridge102 and information about neighbor devices of the hybrid bridge 102. Forexample, the topology message transmitted by the hybrid bridge 102 canindicate that legacy Ethernet devices 114 and 116 are coupled to theEthernet interface 108 and that a legacy PLC device 118 is coupled tothe PLC interface 110. The topology message can also comprise a list ofthe network interfaces through which the hybrid bridge 102 supportsframe forwarding. In one embodiment, if the PLC interface 110 (e.g.,HomePlug AV interface) of the hybrid bridge 102 supports PLC-to-Ethernetbridging, the topology message can include the PLC interface 110 in thelist of network interfaces of the hybrid bridge 102 through which framescan be forwarded. The hybrid bridge 102 can indicate that it supportshybrid bridging through the PLC interface 110 by setting one or morepredetermined bits in a management message transmitted from the PLCinterface 110 (e.g., by setting a bridging station flag (BSF) in aCM_BRG_INFO.CNF management message for a HomePlug AV interface).However, if the PLC interface 110 does not support frame forwarding, thetopology message broadcast by the hybrid bridge 102 may not include thePLC interface 110 in the list of network interfaces of the hybrid bridge102 through which frames can be forwarded. The flow continues at block204.

At block 204, a preferred transmission route for communicating with eachnetwork device of the hybrid communication network is determined. Forexample, the hybrid bridge 102 (e.g., the communication unit 112) cananalyze topology information determined by the hybrid bridge 102 and thetopology messages received from other hybrid devices 122 of the hybridcommunication network 100. The communication unit 112 can estimate thetopology of the hybrid communication network 100 including the locationand interconnection of hybrid devices and legacy devices in the hybridcommunication network 100, the number and type of network interfaces ofthe hybrid devices, which (if any) of the network interfaces of thehybrid devices support frame forwarding, etc. In addition, thecommunication unit 112 can also determine the preferred transmissionroute for communicating with each network device (whether hybrid devicesor legacy devices) in the hybrid communication network 100. In someembodiments, the hybrid bridge 102 can independently determine thepreferred transmission route for itself and all the other hybrid devicesin the communication network based on information (e.g., path metricinformation, traffic information, neighbor device information, etc.)received in the topology messages. In other embodiments, the hybridbridge 102 can determine the preferred transmission route for itself andcan receive an indication of the preferred transmission routesassociated with the other hybrid devices in a preferred route messagereceived from the other hybrid devices. The flow continues at block 206.

At block 206, a loop begins for each network device of the hybridcommunication network. For example, the hybrid bridge 102 (e.g., thehybrid networking sub-layer, the communication unit 112, and/or the PLCinterface 110) can execute the operations described below in blocks208-214 for each network device to determine how to populate the bridgetables 104 and 106 associated with the hybrid bridge 102. In oneembodiment when the hybrid bridge 102 is a PLC-to-Ethernet bridge, thehybrid bridge 102 can execute the operations described below in blocks208-214 for each Ethernet device (e.g., a legacy Ethernet device or ahybrid device with an Ethernet interface) to determine whether toinclude the MAC address of the Ethernet device in the local bridge table104 or the remote bridge table 106 of the hybrid bridge 102. The flowcontinues at block 208.

At block 208, it is determined whether a network interface of the hybridbridge is part of the preferred transmission route to the networkdevice. For example, if the hybrid bridge 102 is a PLC-to-Ethernetbridge, the communication unit 112 can determine whether the PLCinterface 110 (e.g., a HomePlug AV interface) of the hybrid bridge 102is part of the preferred transmission route for communicating with thenetwork device (e.g., the Ethernet device 116). If the network interfaceof the hybrid bridge is part of the preferred transmission route forcommunicating with the network device, the flow continues at block 210.Otherwise, the flow continues at block 214 in FIG. 2B.

At block 210, it is determined whether the network interface of thehybrid bridge is a transmit interface on the preferred transmissionroute to the network device. The flow 200 moves from block 208 to block210 if it is determined that the network interface of the hybrid bridgeis part of the preferred transmission route to the network device. Forexample, if it is determined that the PLC interface 110 of the hybridbridge 102 is on the preferred transmission route to the Ethernet device114, it may be determined whether the PLC interface 110 will be atransmit interface or a receive interface on the preferred communicationroute. If the PLC device 118 generates a frame for transmission to theEthernet device 114, the PLC interface 110 of the hybrid bridge 102 willreceive the frame for forwarding to the Ethernet device 114. In otherwords, in this example, the PLC interface 110 is a receive interface onthe preferred transmission route to the Ethernet device 114. As anotherexample, if the Ethernet device 114 generates a frame for transmissionto the Ethernet device 128, the PLC interface 110 of the hybrid bridge102 will transmit the frame (e.g., to the PLC interface of the hybridbridge 122) for forwarding to the Ethernet device 128. In other words,in this example, the PLC interface 110 is a transmit interface on thepreferred transmission route to the Ethernet device 128. At block 210,if it is determined that the network interface is a receive interface onthe preferred transmission route to the network device, the flowcontinues at block 212. Otherwise, if it is determined that the networkinterface is a transmit interface on the preferred transmission route tothe network device, the flow continues at block 214 in FIG. 2B.

At block 212, a local bridge table associated with the hybrid bridge ispopulated to indicate that the network device is accessible via thenetwork interface of the hybrid bridge. The flow 200 moves from block210 to block 212 if it is determined that the network interface of thehybrid bridge is a receive interface on the preferred transmission routefor communicating with the network device. With reference to the exampleof FIG. 1, the communication unit 112 may determine that the PLCinterface 110 of the hybrid bridge 102 will receive a frame (via thepreferred transmission route) for forwarding to the Ethernet devices 114and 116 (from the Ethernet interface 108 of the hybrid bridge 102). Thecommunication unit 112 can then update/modify the local bridge table 104associated with the PLC interface 110 to include the addresses (e.g., a48-bit MAC address) of the Ethernet devices 114 and 116. As anotherexample, it may be determined that the PLC interface of the hybridbridge 122 will receive a frame (via the preferred transmission route)for forwarding to the Ethernet device 128 (from the Ethernet interfaceof the hybrid bridge 122). Accordingly, the local bridge table 124associated with the PLC interface of the hybrid bridge 122 can beupdated to include the MAC address of the Ethernet device 128. Bypopulating their respective local bridge tables 104 and 124 to beconsistent with their respective receive PLC interfaces that are on thepreferred transmission routes, the hybrid devices 102 and 122 canindirectly influence the legacy devices to transmit frames via thepreferred transmission routes. If the hybrid networking sub-layerpopulates the local bridge table 104 of the hybrid bridge 102, thehybrid networking sub-layer can notify the PLC interface 110 of theupdates to (and content of) the local bridge table 104. The flowcontinues at block 218 in FIG. 2B, where a next network device to beanalyzed (if any) is identified.

At block 214 in FIG. 2B, it is determined that a second bridge device ispart of the preferred transmission route to the network device. The flow200 moves from block 208 in FIG. 2A to block 214 in FIG. 2B if it isdetermined that the network interface of the hybrid bridge is not partof the preferred transmission route for communicating with the networkdevice. For example, the communication unit 112 may determine that thePLC interface 110 of the hybrid bridge 102 is not on the preferredtransmission route to the Ethernet device 128. In FIG. 2, the flow 200also moves from block 210 in FIG. 2A to block 214 in FIG. 2B if it isdetermined that the network interface of the hybrid bridge is a transmitinterface on the preferred transmission route to the network device. Asdiscussed above, the communication unit 112 may determine that the PLCinterface 110 of the hybrid bridge 102 will transmit the frame (e.g., tothe PLC interface of another bridge device) for forwarding to theEthernet device 128. Although the Ethernet device 128 may be reachablevia the Ethernet interface 108 of the hybrid bridge 102, the MAC addressof the Ethernet device 128 may not be recorded in the local bridge table104 if the PLC interface 110 is not part of the preferred transmissionroute to the Ethernet device 128. Instead, the communication unit 112can analyze the preferred transmission route for communicating with theEthernet device 128 and can determine that the PLC interface of a secondbridge device (e.g., the hybrid bridge 122) is part of the preferredtransmission route to the Ethernet device 128. It is noted that thesecond bridge device may be a hybrid bridge (as depicted in FIG. 1) ormay be a legacy/conventional bridge. The flow continues at block 216.

At block 216, a remote bridge table associated with the hybrid bridge ispopulated to indicate that the network device is accessible via thesecond bridge device. For example, as discussed above, the hybrid bridge102 (e.g., the communication unit 112, the hybrid networking sub-layer,and/or the PLC interface 110) may determine that the PLC interface 110of the hybrid bridge 102 is not part of the preferred transmission routeto the Ethernet device 128 and that the PLC interface of the hybridbridge 122 is part of the preferred transmission route to the Ethernetdevice 128. As another example, the hybrid device 102 may determine thatthe PLC interface 110 of the hybrid bridge 102 is a transmit interfaceon the preferred transmission route to the Ethernet device 128 and thatthe PLC interface of the hybrid bridge 122 is a receive interface on thepreferred transmission route to the Ethernet device 128. Thecommunication unit 112 can determine an address (e.g., a 48-bit MACaddress) of the Ethernet device 128 and an identifier (e.g., an 8-bitTEI) of the PLC interface of the hybrid bridge 122. The communicationunit 112 can then create a new entry in the remote bridge table 106comprising the MAC address of the Ethernet device 128 and the TEI of thePLC interface of the hybrid bridge 122, as depicted in FIG. 1. In someembodiments, as discussed above, the hybrid bridge 102 can populate itsremote bridge table 106 based only on knowledge of the preferredtransmission routes associated with each of the network devices of thehybrid communication network 100. If the hybrid networking sub-layerpopulates the remote bridge table 106 of the hybrid bridge 102, thehybrid networking sub-layer can notify the PLC interface 110 of theupdates to (and content of) the remote bridge table 106. The flowcontinues at block 218.

At block 218, it is determined whether additional network devices of thehybrid communication network are to be analyzed. If the hybrid device102 determines that additional network devices of the hybridcommunication network 100 are to be analyzed, the flow loops back toblock 206 in FIG. 2A, where the next network device is identified andthe operations described above with reference to blocks 208-216 areexecuted for the next network device. Otherwise, if it is determinedthat there are no additional network devices to be analyzed, the flowcontinues at block 220.

At block 220, the local bridge table is transmitted from the hybridbridge to other network devices of the hybrid communication network. Forexample, if the hybrid bridge 102 is a PLC-to-Ethernet bridge, thehybrid bridge 102 can transmit the local bridge table 104 on thepowerline network segment 140 of the hybrid communication network 100via the PLC interface 110. For example, if the PLC interface 110 is aHomePlug AV interface, the hybrid bridge 102 can transmit the localbridge table 104 in a CM_BRG_INFO.CNF message via the HomePlug AVinterface. In some embodiments, the hybrid bridge 102 can transmit aunicast message comprising the local bridge table 104 to each PLC devicein the hybrid communication network 100. In this embodiment, the hybridbridge 102 can tailor the local bridge table 104 transmitted to each ofthe PLC devices. In another embodiment, the hybrid bridge 102 cantransmit a broadcast message comprising the local bridge table 104 toall the PLC devices in the hybrid communication network 100.Transmitting the local bridge table 104 on the powerline network segment140 can ensure that other PLC devices (e.g., hybrid devices with a PLCinterface, legacy PLC devices, conventional Ethernet-to-PLC bridges,etc.) receive the local bridge table 104 that was populated based on thepreferred transmission routes of the hybrid bridge 102. The PLC devicesthat receive the local bridge table 104 can populate their respectiveremote bridge tables so that any frames intended for Ethernet deviceslisted in the received local bridge table 104 are transmitted to the PLCinterface 110 of the hybrid bridge 102 for forwarding. From block 220,the flow ends.

FIG. 3 is a flow diagram 300 illustrating example operations for usingthe bridge tables to route a frame to a destination network device. Theflow 300 begins at block 302.

At block 302, a network device of a hybrid communication networkdetermines to transmit a frame to a destination network device of thehybrid communication network. In some embodiments, the network devicemay source the frame that is scheduled for transmission to thedestination network device. With reference to the example of FIG. 1, thelegacy PLC device 118 may generate a frame for transmission to thedestination Ethernet device 116. In other embodiments, the networkdevice may receive the frame (from another network device) forforwarding to the destination network device. With reference to theexample of FIG. 1, the hybrid bridge 102 may receive the frame at itsPLC interface 110 for forwarding to the destination Ethernet device 116.The flow continues at block 304.

At block 304, it is determined whether the network device is abridging-capable device. Typically, only bridging-capable devices (e.g.,either legacy bridges or hybrid bridges) that support frame forwardingmay comprise a local bridge table. As discussed above, if the hybriddevice 102 is configured as a PLC-to-Ethernet bridge, the local bridgetable 104 of the PLC interface 110 of the hybrid bridge 102 can comprisethe addresses of those Ethernet devices 114 and 116 that are reachablefrom the PLC interface 110 via a preferred transmission route. Thus, itmay be determined whether the PLC interface 110 supports bridging orframe forwarding. If it is determined that the network device is abridging-capable device, the flow continues at block 306. Otherwise, theflow continues at block 310.

At block 306, it is determined whether the local bridge table of thenetwork device includes an address of the destination network device.The flow 300 moves from block 304 to block 306 in response todetermining that the network device is a bridging-capable device. Withreference to the example of FIG. 1, the PLC interface 110 of the hybridbridge 102 may receive a frame for forwarding to the destinationEthernet device 116. The PLC interface 110 (or in some embodiments, thehybrid networking sub-layer) can read the MAC address of the destinationEthernet device 116 from the received frame and can determine whetherthe local bridge table 104 (associated with the PLC interface 110)comprises the MAC address of the destination Ethernet device 116. If itis determined that the local bridge table comprises the address of thedestination network device, the flow continues at block 308. Otherwise,the flow continues at block 310.

At block 308, the frame is transmitted to the destination network devicevia an appropriate network interface of the first network device. Theflow 300 moves from block 306 to block 308 if it is determined that thenetwork device is a hybrid bridge and that the local bridge tableincludes the address of the destination network device. With referenceto the example of FIG. 1, if the hybrid bridge 102 is a PLC-to-Ethernetbridge, the PLC interface 110 of the hybrid bridge 102 may receive aframe intended for the destination Ethernet device 116. The PLCinterface 110 can determine that its local bridge table 104 comprisesthe MAC address of the destination Ethernet device 116. The hybridbridge 102 can then forward the frame to the destination Ethernet device116 via the Ethernet interface 108 of the hybrid bridge 102. From block308, the flow ends.

At block 310, a remote bridge table associated with the network deviceis accessed to identify a second bridge device to which to transmit theframe for forwarding to the destination network device. The flow 300moves from block 306 to block 310 if the local bridge table of thehybrid bridge does not include the address of the destination networkdevice. With reference to the example of FIG. 1, the PLC interface 110of the hybrid bridge 102 may receive a frame intended for thedestination Ethernet device 128. The PLC interface 110 may determinethat its local bridge table 104 does not comprise the MAC address of thedestination Ethernet device 128. The PLC interface 110 (or in someembodiments, the hybrid networking sub-layer) can then determine whetherthe remote bridge table 106 (associated with the PLC interface 110)comprises an entry that matches the MAC address of the destinationEthernet device 128. In FIG. 1, the PLC interface 110 (or thecommunication unit 112) can search the remote bridge table 106 and canidentify an entry in the remote bridge table that matches the MACaddress (or another suitable address) of the destination Ethernet device128. The PLC interface 110 (or the communication unit 112) can determinethe TEI (or another suitable address) of the PLC interface of the hybridbridge 122 that corresponds to the destination MAC address in the remotebridge table 106.

With reference to FIG. 3, the flow 300 also moves from block 304 toblock 310 if it is determined that the network device is not a hybridbridge. For example, the legacy PLC device 118 can determine to transmita frame to the destination Ethernet device 116. As similarly discussedabove, the legacy PLC device 118 (e.g., the communication unit 120) canaccess the remote bridge table 130 and can identify an entry in theremote bridge table 130 that matches the address (e.g., a MAC address)of the destination Ethernet device 116. The legacy PLC device 118 candetermine that the destination Ethernet device 116 is reachable from thePLC interface 110 of the hybrid bridge 102. The legacy PLC device 118can also determine the identifier (e.g., the TEI) of the PLC interface110 of the hybrid bridge 102 from the remote bridge table 130. The flowcontinues at block 312.

At block 312, the frame is transmitted to the second bridge device forforwarding to the destination network device. For example, the PLCdevice 118 can determine that the Ethernet device 116 is accessible viathe PLC interface 110 of the hybrid bridge 102 and can determine theidentifier (e.g., the TEI) associated with the PLC interface 110 of thehybrid bridge 102. The PLC device 118 can then insert the identifier ofthe PLC interface 110 and the address (e.g., MAC address) of thedestination Ethernet device 116 in the frame. The PLC device 118 cantransmit the frame to the PLC interface 110 of the hybrid bridge 102 forforwarding to the destination Ethernet device 116. As another example,the PLC interface 110 of the hybrid bridge 102 may determine (based onthe remote bridge table 106) that the Ethernet device 128 is accessiblevia the PLC interface of the hybrid bridge 122. Accordingly, the PLCinterface 110 can transmit the frame to the PLC interface of the hybridbridge 122 for forwarding to the Ethernet device 128. From block 312,the flow ends.

It should be understood that FIGS. 1-3 and the operations describedherein are examples meant to aid in understanding embodiments and shouldnot be used to limit embodiments or limit scope of the claims.Embodiments may perform additional operations, fewer operations,operations in a different order, operations in parallel, and someoperations differently. For example, FIG. 1 depicts the PLC device 118receiving the local bridge tables 104 and 124, and using the receivedlocal bridge tables 104 and 124 to populate the remote bridge table 130associated with the legacy PLC device 118. In some embodiments, thehybrid devices (e.g., the hybrid networking sub-layer of each of thehybrid devices) in the hybrid communication network 100 may populatetheir respective remote bridge tables based on the received topologydiscovery messages, knowledge of the preferred transmission routes, andknowledge of the topology of the hybrid communication network 100.However, in some embodiments, the hybrid devices may populate theirrespective remote bridge tables based on the local bridge tablesreceived from other hybrid devices of the hybrid communication network100.

It is noted that in some embodiments, the preferred transmission routebetween any two network devices (e.g., a PLC device 118 and an Ethernetdevice 114) may vary depending on the frame classification information(e.g., frame stream, the frame type, priority level, source address, andother such factors). For example, the hybrid bridge 102 may be part of(e.g., the PLC interface 110 of the hybrid bridge 102 may be a receiveinterface on) the preferred transmission route to the Ethernet device116 for a first frame stream; while the hybrid bridge 122 may be part of(e.g., the PLC interface of the hybrid bridge 122 may be a receiveinterface on) the preferred transmission route to the same Ethernetdevice 116 for a second frame stream. In this embodiment, the localbridge tables 104 and 124 transmitted by the hybrid devices 102 and 122respectively can also comprise information about the frameclassification information. In some embodiments, the local bridge tables104 and 124 (and consequently the remote bridge tables 106, 126, and130) may be populated to take into account different frame streams,frame types, etc. that may be transmitted. For example, the local bridgetable 104 can include the MAC address of the Ethernet device 116 and anindication of the first frame stream; while the local bridge table 124can include the MAC address of the Ethernet device 116 and an indicationof the second frame stream. The PLC device 118 can populate its remotebridge table 120 so that the PLC device 118 transmits a frame belongingto the first frame stream intended for the Ethernet device 116 to thePLC interface 110 of the hybrid bridge 102 and transmits a framebelonging to the second frame stream intended for the Ethernet device116 to the PLC interface of the hybrid bridge 122.

Although FIG. 1 depicts the legacy PLC device 118 accessing its remotebridge table 130 to determine how to route a frame to the destinationEthernet device 116, in some embodiments, the PLC interface 110 of thehybrid bridge 102 may determine to transmit the frame to a destinationEthernet device. In this embodiment, the PLC interface 110 of the hybridbridge 102 can first check the local bridge table 104 (associated withthe PLC interface 110) to determine whether the destination Ethernetdevice (e.g., the Ethernet device 116) is directly reachable from theEthernet interface 108 of the hybrid bridge 102 via a preferredtransmission route. If so, the frame can be directly transmitted to thedestination Ethernet device 116 via the Ethernet interface 108 of thehybrid bridge 102. However, if the destination Ethernet device (e.g.,the Ethernet device 128) is not listed in the local bridge table 104,then the Ethernet device 128 is not reachable from the Ethernetinterface 108 of the hybrid bridge 102 via the preferred transmissionroute. Accordingly, the PLC interface 110 can access the remote bridgetable 106 (associated with the PLC interface 110) and can identify adevice identifier (e.g., a TEI) of the PLC interface of another hybridbridge 122 via which the destination Ethernet device 128 can be accessedvia the preferred transmission route, as described above in stages C andD of FIG. 1.

In some embodiments as discussed above, the hybrid bridge 122 may not bepart of the preferred transmission route to an Ethernet device 116 eventhough the Ethernet device 116 may be coupled with the hybrid bridge122. For example, the Ethernet device 116 may be connected to both thehybrid bridges 102 and 122. The PLC interface 110 of the hybrid bridge102 may a receive interface on the preferred transmission route to theEthernet device 116 while the PLC interface of the hybrid bridge 122 maynot be part of (or may be a transmit interface on) the preferredtransmission route to the Ethernet device 116. In this embodiment, evenif the PLC interface of the hybrid bridge 122 receives a frame intendedfor the Ethernet device 116, the hybrid bridge 122 may not directlytransmit the frame to the Ethernet device 116. Instead, the hybriddevice 122 may provide the frame to the PLC interface 110 of the hybridbridge 102 (e.g., via the powerline network segment) and the hybridbridge 102 may forward the frame to the Ethernet device 116 via thepreferred transmission route.

Although not depicted in FIGS. 1 and 3, it is noted that in someembodiments, the remote bridge table 130 of the PLC device 118 may notcomprise an entry that matches the address of the destination Ethernetdevice 116. In this embodiment, the PLC device 118 can broadcast theframe on the powerline network segment using a broadcast destinationidentifier (e.g., a broadcast TEI). The hybrid bridges 102 and 122 mayreceive the broadcast frame at their respective PLC interfaces. Thehybrid bridges 102 and 122 can access their respective bridge tables todetermine how to route the frame to the destination Ethernet device. Ifthe local bridge table or the remote bridge table associated with one ofthe hybrid devices 102 and 122 comprises the address of the destinationEthernet device 116, the hybrid bridge can forward the frame to thedestination Ethernet device 116 via an appropriate network interface.However, if the local bridge tables and the remote bridge tablesassociated with the hybrid bridges 102 and 122 do not comprise an entrythat matches the address of the destination Ethernet device 116, thehybrid devices 102 and 122 can re-broadcast the received frame via theirrespective Ethernet interfaces. It is also noted that broadcast framesand multicast frames received at the PLC interface 110 of the hybridbridge 102 can be re-broadcast on the Ethernet segment via the Ethernetinterface 108. Furthermore, broadcast frames and multicast framesreceived at the Ethernet interface 108 of the hybrid bridge 102 can bere-broadcast on the powerline network segment via the PLC interface 110.

In some embodiments, the hybrid bridge 102 may only receive those framesthrough its PLC (e.g., HomePlug AV) interface 110 where the MACdestination address indicated in the received frame matches the MACaddress of the PLC interface 110. In this embodiment, the hybrid bridge102 (and the PLC interface 110) may not present itself to the powerlinenetwork segment as a PLC-to-Ethernet bridge. The hybrid bridge 102 mayindicate that it does not support PLC-to-Ethernet bridging by settingone or more bits in a management message (e.g., by not setting the BSF)and may not generate or transmit its local bridge table(s) to other PLCdevices. Alternately, in this embodiment, the hybrid bridge 102 canpresent itself to the powerline network segment as a PLC-to-Ethernetbridge, can indicate that it supports PLC-to-Ethernet bridging, and cangenerate and transmit the local bridge table comprising the MAC addressof the PLC interface of the hybrid bridge 102.

In accordance with the powerline communication protocol (e.g., HomePlugAV protocol), an 8-bit terminal equipment identifier (TEI) can bedynamically assigned to each PLC device (e.g., the PLC device 118, thePLC interface 110 of the hybrid bridge 102, etc.) in the local powerlinenetwork segment. A transmitter PLC device can use the TEI of a receiverPLC device to transmit a frame to the receiver PLC device and thereceiver PLC device can accept/discard a frame depending on the TEIindicated in the received frame. In some embodiments, the TEI may beunique to the PLC device only within the powerline network segmentwithin the hybrid communication network 100. In addition, each of thePLC devices (e.g., the hybrid devices or the legacy PLC devices) canalso have a universal identifier (e.g., a 48-bit address) that is uniqueacross all types of networks, communication technologies, and devices.In some embodiments, when the upper protocol layers (e.g., the networklayer, the transport layer, or the application layer in an open systemsinterconnection (OSI) model) of the hybrid bridge 122 generate a frame,the frame can comprise the 48-bit address of the destination Ethernetdevice 114. The PLC interface (e.g., the HomePlug AV interface) of thePLC device 118 can identify the TEI of the PLC interface 110 of thehybrid bridge from the remote bridge table 130, can encapsulate theframe in a PLC header that includes the TEI of the PLC interface 110,and can transmit the frame to the PLC interface 110 on the powerlinenetwork.

It is also noted that in some embodiments, the local bridge tables(e.g., the LBDAT) and the remote bridge tables (e.g., the RBAT) areassociated with PLC interfaces (e.g., HomePlug AV interfaces) and MoCAinterfaces. In one example, if a hybrid bridge comprises a HomePlug AVinterface, a MoCA interface, and an Ethernet interface, the hybridbridge can comprise two local bridge tables and two remote bridgetables—one each for the HomePlug AV interface and the MoCA interfacerespectively.

As will be appreciated by one skilled in the art, aspects of the presentinventive subject matter may be embodied as a system, method, orcomputer program product. Accordingly, aspects of the present inventivesubject matter may take the form of an entirely hardware embodiment, asoftware embodiment (including firmware, resident software, micro-code,etc.) or an embodiment combining software and hardware aspects that mayall generally be referred to herein as a “circuit,” “module” or“system.” Furthermore, aspects of the present inventive subject mattermay take the form of a computer program product embodied in one or morecomputer readable medium(s) having computer readable program codeembodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent inventive subject matter may be written in any combination ofone or more programming languages, including an object orientedprogramming language such as Java®, Smalltalk, C++ or the like andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The program codemay execute entirely on the user's computer, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

Aspects of the present inventive subject matter are described withreference to flowchart illustrations and/or block diagrams of methods,apparatus (systems) and computer program products according toembodiments of the inventive subject matter. It will be understood thateach block of the flowchart illustrations and/or block diagrams, andcombinations of blocks in the flowchart illustrations and/or blockdiagrams, can be implemented by computer program instructions. Thesecomputer program instructions may be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

FIG. 4 is a block diagram of one embodiment of an electronic device 400including a mechanism for bridging network devices in a hybridcommunication network. In some embodiments, the electronic device 400can be a laptop computer, a tablet computer, a netbook, a mobile phone,a smart appliance, a gaming console, a desktop computer, or othersuitable electronic device comprising communication capabilities. Theelectronic device 400 includes a processor unit 402 (possibly includingmultiple processors, multiple cores, multiple nodes, and/or implementingmulti-threading, etc.). The electronic device 400 includes a memory unit406. The memory unit 406 may be system memory (e.g., one or more ofcache, SRAM, DRAM, zero capacitor RAM, Twin Transistor RAM, eDRAM, EDORAM, DDR RAM, EEPROM, NRAM, RRAM, SONOS, PRAM, etc.) or any one or moreof the above already described possible realizations of machine-readablestorage media. The electronic device 400 also includes a bus 410 (e.g.,PCI, ISA, PCI-Express, HyperTransport®, InfiniBand®, NuBus, AHB, AXI,etc.), and network interfaces 404 that include at least one of awireless network interface (e.g., a WLAN interface, a Bluetooth®interface, a WiMAX interface, a ZigBee® interface, a Wireless USBinterface, etc.) and a wired network interface (e.g., a powerlinecommunication interface, an Ethernet interface, etc.).

The electronic device 400 also includes a communication unit 408. Thecommunication unit 408 can execute functionality described above withreference to FIGS. 1-3 to selectively populate the local bridge tableand the remote bridge table based on whether the electronic device 400is part of the preferred transmission route for communicating with othernetwork devices. The communication unit 408 can transmit the localbridge table to influence legacy network devices to populate theirrespective remote bridge tables and to transmit frames based on thepreferred transmission routes. Any one of these functionalities may bepartially (or entirely) implemented in hardware and/or on the processorunit 402. For example, the functionality may be implemented with anapplication specific integrated circuit, in logic implemented in theprocessor unit 402, in a co-processor on a peripheral device or card,etc. Further, realizations may include fewer or additional componentsnot illustrated in FIG. 4 (e.g., video cards, audio cards, additionalnetwork interfaces, peripheral devices, etc.). For example, thecommunication unit 408 may comprise one or more additional processorsthat are distinct from the processor unit 402 coupled with the bus 410.The processor unit 402, the memory unit 406, and the network interfaces404 are coupled to the bus 410. Although illustrated as being coupled tothe bus 410, the memory unit 406 may be coupled to the processor unit402.

While the embodiments are described with reference to variousimplementations and exploitations, it will be understood that theseembodiments are illustrative and that the scope of the inventive subjectmatter is not limited to them. In general, techniques for bridgingnetwork devices in a hybrid communication network as described hereinmay be implemented with facilities consistent with any hardware systemor hardware systems. Many variations, modifications, additions, andimprovements are possible.

Plural instances may be provided for components, operations, orstructures described herein as a single instance. Finally, boundariesbetween various components, operations, and data stores are somewhatarbitrary, and particular operations are illustrated in the context ofspecific illustrative configurations. Other allocations of functionalityare envisioned and may fall within the scope of the inventive subjectmatter. In general, structures and functionality presented as separatecomponents in the exemplary configurations may be implemented as acombined structure or component. Similarly, structures and functionalitypresented as a single component may be implemented as separatecomponents. These and other variations, modifications, additions, andimprovements may fall within the scope of the inventive subject matter.

What is claimed is:
 1. A method comprising: determining a preferredtransmission route for communicating with a first of a plurality ofnetwork devices of a hybrid communication network, wherein saiddetermining the preferred transmission route is: at a hybrid networklayer of a hybrid bridge device of the hybrid communication network, andbased, at least in part, on one or more topology discovery messagesreceived from one or more of the plurality of network devices;determining whether the hybrid bridge device is part of the preferredtransmission route associated with the first of the plurality of networkdevices, wherein said determining whether the hybrid bridge device ispart of the preferred transmission route is: at the hybrid networklayer, and based, at least in part, on said determining the preferredtransmission route; and populating a bridge table associated with thehybrid bridge device with an identifier associated with the first of theplurality of network devices, wherein said populating the bridge tableis: based on whether the hybrid bridge device is part of the preferredtransmission route associated with the first of the plurality of networkdevices.
 2. The method of claim 1, wherein if determined that the hybridbridge device is part of the preferred transmission route associatedwith the first of the plurality of network devices, the method furthercomprises: determining whether a first network interface of a pluralityof network interfaces of the hybrid bridge device is a receive interfaceon the preferred transmission route for communicating with the first ofthe plurality of network devices; if determined that the first networkinterface of the hybrid bridge device is a receive interface on thepreferred transmission route for communicating with the first of theplurality of network devices, said populating the bridge tableassociated with the hybrid bridge device comprises populating, at thehybrid network layer, a local bridge table associated with the firstnetwork interface of the hybrid bridge device with an identifierassociated with the first of the plurality of network devices.
 3. Themethod of claim 2, wherein, if determined that the first networkinterface of the hybrid bridge device is part of the preferredtransmission route, the method further comprises: if determined that thefirst network interface of the hybrid bridge device is a transmitinterface on the preferred transmission route for communicating with thefirst of the plurality of network devices, determining that a networkbridge device of the plurality of network devices is part of thepreferred transmission route associated with the first of the pluralityof network devices, wherein said determining that the network bridgedevice is part of the preferred transmission route is: at the hybridnetwork layer of the hybrid bridge device, and based, at least in part,on the received topology discovery messages and the preferredtransmission route for communicating with the first of the plurality ofnetwork devices; and populating, at the hybrid network layer of thehybrid bridge device, a remote bridge table associated with the firstnetwork interface of the hybrid bridge device such that the remotebridge table comprises at least one association between the identifierof the first of the plurality of network devices and a device identifierof the network bridge device, wherein the hybrid bridge devicetransmits, via the network bridge device, a frame destined for the firstof the plurality of network devices.
 4. The method of claim 2, whereinsaid populating the bridge table associated with the hybrid bridgedevice with the identifier associated with the first of the plurality ofnetwork devices comprises: if determined that the first networkinterface of the hybrid bridge device is not part of the preferredtransmission route associated with the first of the plurality of networkdevices, determining, at the hybrid network layer, not to populate thelocal bridge table associated with the first network interface of thehybrid bridge device with the identifier associated with the first ofthe plurality of network devices.
 5. The method of claim 2, wherein saidpopulating the local bridge table associated with the first networkinterface of the hybrid bridge device comprises: populating the localbridge table associated with the first network interface of the hybridbridge device with the identifier associated with the first of theplurality of network devices and frame classification informationassociated with frames that are scheduled to be transmitted from thefirst network interface of the hybrid bridge device to the first of theplurality of network devices of the hybrid communication network.
 6. Themethod of claim 5, wherein the frame classification informationcomprises one or more of a frame stream, a frame type, a frame prioritylevel, and a source address.
 7. The method of claim 2, wherein ifdetermined that the hybrid bridge device is not part of the preferredtransmission route associated with the first of the plurality of networkdevices, the method comprises: determining that a network bridge deviceof the plurality of network devices is part of the preferredtransmission route associated with the first of the plurality of networkdevices, wherein said determining that the network bridge device is partof the preferred transmission route is: at the hybrid network layer ofthe hybrid bridge device, and based, at least in part, on the receivedtopology discovery messages and the preferred transmission route forcommunicating with the first of the plurality of network devices; andsaid populating the bridge table associated with the hybrid bridgedevice comprises populating, at the hybrid network layer of the hybridbridge device, a remote bridge table of the first network interface ofthe hybrid bridge device such that the remote bridge table comprises atleast one association between the identifier of the first of theplurality of network devices and a device identifier of the networkbridge device, wherein the hybrid bridge device transmits, via thenetwork bridge device, a frame destined for the first of the pluralityof network devices.
 8. The method of claim 7, wherein the deviceidentifier of the network bridge device is an address of a first of aplurality of network interfaces of a second bridge device, wherein thehybrid bridge device is coupled with the first of the plurality ofnetwork interfaces of the network bridge device; and wherein the firstof the plurality of network devices is coupled with a second of theplurality of network interfaces of the network bridge device.
 9. Themethod of claim 7, wherein the identifier of the first of the pluralityof network devices of the hybrid communication network is a media accesscontrol (MAC) address and the device identifier of the network bridgedevice of the hybrid communication network is a terminal equipmentidentifier (TEI).
 10. The method of claim 1, wherein said determiningwhether the hybrid bridge device is part of the preferred transmissionroute associated with the first of the plurality of network devices andsaid populating the bridge table associated with the hybrid bridgedevice comprises: determining, at the hybrid network layer of the hybridbridge device, that a frame stream is scheduled to be transmitted fromthe hybrid bridge device to the first of the plurality of networkdevices of the hybrid communication network; determining the preferredtransmission route for transmitting the frame stream to the first of theplurality of network devices; determining whether a first networkinterface of a plurality of network interfaces of the hybrid bridgedevice is part of the preferred transmission route for transmitting theframe stream to the first of the plurality of network devices; ifdetermined that the first network interface of the hybrid bridge deviceis part of the preferred transmission route for transmitting the framestream to the first of the plurality of network devices, determiningwhether the first network interface of the hybrid bridge device is areceive interface on the preferred transmission route for transmittingthe frame stream to the first of the plurality of network devices; ifdetermined that the first network interface of the hybrid bridge deviceis a receive interface on the preferred transmission route, populating alocal bridge table associated with the first network interface of thehybrid bridge device with the identifier associated with the first ofthe plurality of network devices and an indication of the frame stream;if determined that the first network interface of the hybrid bridgedevice is not part of the preferred transmission route for transmittingthe frame stream to the first of the plurality of network devices or ifdetermined that the first network interface of the hybrid bridge deviceis a transmit interface on the preferred transmission route fortransmitting the frame stream to the first of the plurality of networkdevices, identifying a network bridge device of the plurality of networkdevices that is part of the preferred transmission route fortransmitting the frame stream to the first of the plurality of networkdevices; and creating, in a remote bridge table of the first networkinterface of the hybrid bridge device, an entry associated with theframe stream to indicate an association between the identifier of thefirst of the plurality of network devices, a device identifier of thenetwork bridge device, and the indication of the frame stream, whereinthe hybrid bridge device transmits a frame belonging to the frame streamto the first of the plurality of network devices via the network bridgedevice.
 11. The method of claim 1, further comprising: determining totransmit a frame to the first of the plurality of network devices of thehybrid communication network; determining whether a local bridge tableof the hybrid bridge device comprises the identifier associated with thefirst of the plurality of network devices; if determined that the localbridge table of the hybrid bridge device comprises the identifierassociated with the first of the plurality of network devices,transmitting the frame to the first of the plurality of network devicesvia a first of a plurality of network interfaces of the hybrid bridgedevice indicated by the local bridge table; if determined that the localbridge table of the hybrid bridge device does not comprise theidentifier associated with the first of the plurality of networkdevices, determining whether a remote bridge table of the hybrid bridgedevice comprises an association between the first of the plurality ofnetwork devices and a network bridge device of the plurality of networkdevices of the hybrid communication network; if determined that theremote bridge table of the hybrid bridge device comprises theassociation between the first of the plurality of network devices andthe network bridge device of the plurality of network devices,transmitting the frame to the network bridge device from a second of theplurality of network interfaces of the hybrid bridge device forforwarding to the first of the plurality of network devices; and ifdetermined that the remote bridge table of the hybrid bridge device doesnot comprise the association between the first of the plurality ofnetwork devices and the network bridge device of the plurality ofnetwork devices, broadcasting the frame from the first of the pluralityof network interfaces of the hybrid bridge device.
 12. The method ofclaim 11, wherein if the hybrid bridge device is a powerlinecommunication (PLC)-to-Ethernet bridge device, said determining totransmit the frame to the first of the plurality of network devices ofthe hybrid communication network is in response to receiving the frameat a PLC interface of the hybrid bridge device for transmission to anEthernet device of the plurality of network devices.
 13. The method ofclaim 1, wherein said determining the preferred transmission route forcommunicating with the first of the plurality of network devices of thehybrid communication network comprises: determining, based at least inpart on the one or more topology discovery messages received from theplurality of network devices of the hybrid communication network, aplurality of preferred transmission routes for communicating withcorresponding ones of the plurality of network devices of the hybridcommunication network; and said determining whether the hybrid bridgedevice is part of the preferred transmission route associated with thefirst of the plurality of network devices comprises: determining, basedat least in part on said determining the plurality of preferredtransmission routes for communicating with corresponding ones of theplurality of network devices, whether a first network interface of thehybrid bridge device is part of each of the plurality of preferredtransmission routes associated with corresponding ones of the pluralityof network devices.
 14. The method of claim 1, further comprisingtransmitting the bridge table via a first of a plurality of networkinterfaces of the hybrid bridge device that is configured for frameforwarding.
 15. The method of claim 1, further comprising: transmittinga topology discovery message associated with the hybrid bridge device tothe plurality of network devices of the hybrid communication network,wherein the topology discovery message comprises at least one of anindication of one or more of a plurality of network interfaces of thehybrid bridge device that support frame forwarding and a preferredtransmission route associated with each of the one or more of theplurality of network interfaces of the hybrid bridge device.
 16. One ormore machine-readable storage media having instructions stored therein,which when executed by one or more processors causes the one or moreprocessors to perform operations that comprise: determining a preferredtransmission route for communicating with a first of a plurality ofnetwork devices of a hybrid communication network, wherein saidoperation of determining the preferred transmission route is: at ahybrid network layer of a hybrid bridge device of the hybridcommunication network, and based, at least in part, on one or moretopology discovery messages received from one or more of the pluralityof network devices; determining whether the hybrid bridge device is partof the preferred transmission route associated with the first of theplurality of network devices, wherein said operation of determiningwhether the hybrid bridge device is part of the preferred transmissionroute is: based, at least in part, on said operation of determining thepreferred transmission route; and populating a bridge table associatedwith the hybrid bridge device with an identifier associated with thefirst of the plurality of network devices, wherein said operation ofpopulating the bridge table is: based on whether the hybrid bridgedevice is part of the preferred transmission route associated with thefirst of the plurality of network devices.
 17. The machine-readablestorage media of claim 16, wherein if determined that the hybrid bridgedevice is part of the preferred transmission route associated with thefirst of the plurality of network devices, the operations comprise:determining whether a first network interface of a plurality of networkinterfaces of the hybrid bridge device is a receive interface on thepreferred transmission route for communicating with the first of theplurality of network devices; if determined that the first networkinterface of the hybrid bridge device is a receive interface on thepreferred transmission route for communicating with the first of theplurality of network devices, said operation of populating the bridgetable associated with the hybrid bridge device comprises populating, atthe hybrid network layer, a local bridge table associated with the firstnetwork interface of the hybrid bridge device with an identifierassociated with the first of the plurality of network devices.
 18. Themachine-readable storage media of claim 17, wherein, if determined thatthe first network interface of the hybrid bridge device is part of thepreferred transmission route, the operations further comprise: ifdetermined that the first network interface of the hybrid bridge deviceis a transmit interface on the preferred transmission route forcommunicating with the first of the plurality of network devices,determining that a network bridge device of the plurality of networkdevices is part of the preferred transmission route associated with thefirst of the plurality of network devices, wherein said operation ofdetermining that the network bridge device is part of the preferredtransmission route is: at the hybrid network layer of the hybrid bridgedevice, and based, at least in part, on the received topology discoverymessages and the preferred transmission route for communicating with thefirst of the plurality of network devices; and populating, at the hybridnetwork layer of the hybrid bridge device, a remote bridge tableassociated with the first network interface of the hybrid bridge devicesuch that the remote bridge table comprises at least one associationbetween the identifier of the first of the plurality of network devicesand a device identifier of the network bridge device, wherein the hybridbridge device transmits, via the network bridge device, a frame destinedfor the first of the plurality of network devices.
 19. Themachine-readable storage media of claim 17, wherein said operation ofpopulating the local bridge table associated with the first networkinterface of the hybrid bridge device comprises: populating the localbridge table associated with the first network interface of the hybridbridge device with the identifier associated with the first of theplurality of network devices and frame classification informationassociated with frames that are scheduled to be transmitted from thefirst network interface of the hybrid bridge device to the first of theplurality of network devices of the hybrid communication network. 20.The machine-readable storage media of claim 17, wherein if determinedthat the hybrid bridge device is not part of the preferred transmissionroute associated with the first of the plurality of network devices, theoperations further comprise: determining that a network bridge device ofthe plurality of network devices is part of the preferred transmissionroute associated with the first of the plurality of network devices,wherein said operation of determining that the network bridge device ispart of the preferred transmission route is: at the hybrid bridgedevice, and based, at least in part, on the received topology discoverymessages and the preferred transmission route for communicating with thefirst of the plurality of network devices; and said operation ofpopulating the bridge table associated with the hybrid bridge devicecomprises populating, at the hybrid bridge device, a remote bridge tableof the first network interface of the hybrid bridge device such that theremote bridge table comprises at least one association between theidentifier of the first of the plurality of network devices and a deviceidentifier of the network bridge device, wherein the hybrid bridgedevice transmits, via the network bridge device, a frame destined forthe first of the plurality of network devices.
 21. The machine-readablestorage media of claim 16, wherein said operation of determining whetherthe hybrid bridge device is part of the preferred transmission routeassociated with the first of the plurality of network devices and saidoperation of populating the bridge table associated with the hybridbridge device comprises: determining, at the hybrid bridge device, thata frame stream is scheduled to be transmitted from the hybrid bridgedevice to the first of the plurality of network devices of the hybridcommunication network; determining the preferred transmission route fortransmitting the frame stream to the first of the plurality of networkdevices; determining whether a first network interface of a plurality ofnetwork interfaces of the hybrid bridge device is part of the preferredtransmission route for transmitting the frame stream to the first of theplurality of network devices; if determined that the first networkinterface of the hybrid bridge device is part of the preferredtransmission route for transmitting the frame stream to the first of theplurality of network devices, determining whether the first networkinterface of the hybrid bridge device is a receive interface on thepreferred transmission route for transmitting the frame stream to thefirst of the plurality of network devices; if determined that the firstnetwork interface of the hybrid bridge device is a receive interface onthe preferred transmission route, populating a local bridge tableassociated with the first network interface of the hybrid bridge devicewith the identifier associated with the first of the plurality ofnetwork devices and an indication of the frame stream; if determinedthat the first network interface of the hybrid bridge device is not partof the preferred transmission route for transmitting the frame stream tothe first of the plurality of network devices or if determined that thefirst network interface of the hybrid bridge device is a transmitinterface on the preferred transmission route for transmitting the framestream to the first of the plurality of network devices, identifying anetwork bridge device of the plurality of network devices that is partof the preferred transmission route for transmitting the frame stream tothe first of the plurality of network devices; and creating, in a remotebridge table of the first network interface of the hybrid bridge device,an entry associated with the frame stream to indicate an associationbetween the identifier of the first of the plurality of network devices,a device identifier of the network bridge device, and the indication ofthe frame stream, wherein the hybrid bridge device transmits a framebelonging to the frame stream to the first of the plurality of networkdevices via the network bridge device.
 22. The machine-readable storagemedia of claim 16, wherein the operations further comprise: determiningto transmit a frame to the first of the plurality of network devices ofthe hybrid communication network; determining whether a local bridgetable of the hybrid bridge device comprises the identifier associatedwith the first of the plurality of network devices; if determined thatthe local bridge table of the hybrid bridge device comprises theidentifier associated with the first of the plurality of networkdevices, transmitting the frame to the first of the plurality of networkdevices via a first of a plurality of network interfaces of the hybridbridge device indicated by the local bridge table; if determined thatthe local bridge table of the hybrid bridge device does not comprise theidentifier associated with the first of the plurality of networkdevices, determining whether a remote bridge table of the hybrid bridgedevice comprises an association between the first of the plurality ofnetwork devices and a network bridge device of the plurality of networkdevices of the hybrid communication network; if determined that theremote bridge table of the hybrid bridge device comprises theassociation between the first of the plurality of network devices andthe network bridge device of the plurality of network devices,transmitting the frame to the network bridge device from a second of theplurality of network interfaces of the hybrid bridge device forforwarding to the first of the plurality of network devices; and ifdetermined that the remote bridge table of the hybrid bridge device doesnot comprise the association between the first of the plurality ofnetwork devices and the network bridge device of the plurality ofnetwork devices, broadcasting the frame from the first of the pluralityof network interfaces of the hybrid bridge device.
 23. A hybrid bridgedevice comprising: a plurality of network interfaces; and acommunication unit coupled with the plurality of network interfaces, thecommunication unit operable to: determine a preferred transmission routefor communicating with a first of a plurality of network devices of ahybrid communication network, wherein the communication unit operable todetermine the preferred transmission route is: based, at least in part,on one or more topology discovery messages received from one or more ofthe plurality of network devices; determine whether the hybrid bridgedevice is part of the preferred transmission route associated with thefirst of the plurality of network devices, wherein the communicationunit operable to determine whether the hybrid bridge device is part ofthe preferred transmission route is: based, at least in part, on thecommunication unit determining the preferred transmission route; andpopulate a bridge table associated with the hybrid bridge device with anidentifier associated with the first of the plurality of networkdevices, wherein the communication unit operable to populate the bridgetable is: based on whether the hybrid bridge device is part of thepreferred transmission route associated with the first of the pluralityof network devices.
 24. The hybrid bridge device of claim 23, wherein ifdetermined that the hybrid bridge device is part of the preferredtransmission route associated with the first of the plurality of networkdevices, the communication unit is operable to: determine whether afirst network interface of the plurality of network interfaces of thehybrid bridge device is a receive interface on the preferredtransmission route for communicating with the first of the plurality ofnetwork devices; if determined that the first network interface is areceive interface on the preferred transmission route for communicatingwith the first of the plurality of network devices, the communicationunit operable to populate the bridge table associated with the hybridbridge device comprises the communication unit operable to populate alocal bridge table associated with the first network interface of thehybrid bridge device with an identifier associated with the first of theplurality of network devices.
 25. The hybrid bridge device of claim 24,wherein, if determined that the first network interface of the hybridbridge device is part of the preferred transmission route, thecommunication unit is operable to: if determined that the first networkinterface is a transmit interface on the preferred transmission routefor communicating with the first of the plurality of network devices,determine that a network bridge device of the plurality of networkdevices is part of the preferred transmission route associated with thefirst of the plurality of network devices, wherein the communicationunit operable to determine that the network bridge device is part of thepreferred transmission route is: based, at least in part, on thereceived topology discovery messages and the preferred transmissionroute for communicating with the first of the plurality of networkdevices; and populate a remote bridge table associated with the firstnetwork interface such that the remote bridge table comprises at leastone association between the identifier of the first of the plurality ofnetwork devices and a device identifier of the network bridge device,wherein the hybrid bridge device transmits, via the network bridgedevice, a frame destined for the first of the plurality of networkdevices
 26. The hybrid bridge device of claim 24, wherein if determinedthat the hybrid bridge device is not part of the preferred transmissionroute associated with the first of the plurality of network devices, thecommunication unit is operable to: determine that a network bridgedevice of the plurality of network devices is part of the preferredtransmission route associated with the first of the plurality of networkdevices, wherein the communication unit operable to determine that thenetwork bridge device is part of the preferred transmission route is:based, at least in part, on the received topology discovery messages andthe preferred transmission route for communicating with the first of theplurality of network devices; and the communication unit operable to thebridge table associated with the hybrid bridge device comprisescommunication unit operable to populate a remote bridge table of thefirst network interface of the hybrid bridge device such that the remotebridge table comprises at least one association between the identifierof the first of the plurality of network devices and a device identifierof the network bridge device, wherein the hybrid bridge devicetransmits, via the network bridge device, a frame destined for the firstof the plurality of network devices.
 27. The hybrid bridge device ofclaim 23, wherein the communication unit operable to determine whetherthe hybrid bridge device is part of the preferred transmission routeassociated with the first of the plurality of network devices and thecommunication unit operable to populate the bridge table associated withthe hybrid bridge device comprises the communication unit operable to:determine that a frame stream is scheduled to be transmitted from thehybrid bridge device to the first of the plurality of network devices ofthe hybrid communication network; determine the preferred transmissionroute for transmitting the frame stream to the first of the plurality ofnetwork devices; determine whether a first network interface of aplurality of network interfaces of the hybrid bridge device is part ofthe preferred transmission route for transmitting the frame stream tothe first of the plurality of network devices; if determined that thefirst network interface of the hybrid bridge device is part of thepreferred transmission route for transmitting the frame stream to thefirst of the plurality of network devices, determine whether the firstnetwork interface of the hybrid bridge device is a receive interface onthe preferred transmission route for transmitting the frame stream tothe first of the plurality of network devices; if determined that thefirst network interface of the hybrid bridge device is a receiveinterface on the preferred transmission route, populate a local bridgetable associated with the first network interface of the hybrid bridgedevice with the identifier associated with the first of the plurality ofnetwork devices and an indication of the frame stream; if determinedthat the first network interface of the hybrid bridge device is not partof the preferred transmission route for transmitting the frame stream tothe first of the plurality of network devices or if determined that thefirst network interface of the hybrid bridge device is a transmitinterface on the preferred transmission route for transmitting the framestream to the first of the plurality of network devices, identify anetwork bridge device of the plurality of network devices that is partof the preferred transmission route for transmitting the frame stream tothe first of the plurality of network devices; and create, in a remotebridge table of the first network interface of the hybrid bridge device,an entry associated with the frame stream to indicate an associationbetween the identifier of the first of the plurality of network devices,a device identifier of the network bridge device, and the indication ofthe frame stream, wherein the hybrid bridge device transmits a framebelonging to the frame stream to the first of the plurality of networkdevices via the network bridge device.
 28. The hybrid bridge device ofclaim 23, wherein the communication unit is further operable to:determine to transmit a frame to the first of the plurality of networkdevices of the hybrid communication network; determine whether a localbridge table of the hybrid bridge device comprises the identifierassociated with the first of the plurality of network devices; ifdetermined that the local bridge table of the hybrid bridge devicecomprises the identifier associated with the first of the plurality ofnetwork devices, transmit the frame to the first of the plurality ofnetwork devices via a first of a plurality of network interfaces of thehybrid bridge device indicated by the local bridge table; if determinedthat the local bridge table of the hybrid bridge device does notcomprise the identifier associated with the first of the plurality ofnetwork devices, determine whether a remote bridge table of the hybridbridge device comprises an association between the first of theplurality of network devices and a network bridge device of theplurality of network devices of the hybrid communication network; ifdetermined that the remote bridge table of the hybrid bridge devicecomprises the association between the first of the plurality of networkdevices and the network bridge device of the plurality of networkdevices, transmit the frame to the network bridge device from a secondof the plurality of network interfaces of the hybrid bridge device forforwarding to the first of the plurality of network devices; and ifdetermined that the remote bridge table of the hybrid bridge device doesnot comprise the association between the first of the plurality ofnetwork devices and the network bridge device of the plurality ofnetwork devices, broadcast the frame from the first of the plurality ofnetwork interfaces of the hybrid bridge device.
 29. The hybrid bridgedevice of claim 23, further comprising a local bridge table coupled tothe communication unit, wherein the local bridge table comprises theidentifier of the first of the plurality of network devices when a firstnetwork interface of the hybrid bridge device is a receive interface onthe preferred transmission route associated with the first of theplurality of network devices.
 30. The hybrid bridge device of claim 23,further comprising: a local bridge table coupled to the communicationunit, wherein the local bridge table comprises the identifier of thefirst of the plurality of network devices when a first network interfaceof the hybrid bridge device is a receive interface on the preferredtransmission route associated with the first of the plurality of networkdevices; and a remote bridge table coupled to the communication unit,wherein the remote bridge table comprises an identifier of a second ofthe plurality of network devices and an interface address of a secondbridge device, when the first network interface of the hybrid bridgedevice is a transmit interface on the preferred transmission routeassociated with the second of the plurality of network devices or thefirst network interface of the hybrid bridge device is not part of thepreferred transmission route associated with the second of the pluralityof network devices.